Oxidative Phosphorylation Flashcards
Where is oxidative phosphorylation taking place in the cell?
Inner mitochondrial membrane.
What is the simple chemical reaction that powers ATPsynthase?
ADP +Pi coupled with H+ electron gradient.
Explain how protonmotive force works. What else is associated with it and how much influence does that have as well?
Pmf= proton motive force
For each pair of electrons that enter the ETC from NADH, how many protons are pumped out of the matrix? Which complex produces how many H+? How much energy does it give us in the cell? How much energy does it take to synthesize ATP in the cell.
Name the two complexes that make up ATP synthase protein. What side do they reside on?
There are two subunits for Fo complex, and 4 for F1 complex. Name them all.
(What’s the third complex as well? 4 subunits)
Is a membrane protein.
Stator is like rotary motor.
What subunits of ATP synthase move(4)? Which ones are stationary(3)?
Note: can be used in reverse! Video shows how it makes 120° rotations.
Explain glutamates role in ATP synthesis.
Glutamate in most hydrophobic part of membrane layer, next to a subunit, in between 2 subunits/half channels.
They both connect to C ring glutamate residue.
Protonates glutamate, which makes it happy enough to move into the belayer enough to rotate into membrane. New glutamate gets protonated, rotates again, once glutamate reaches second half channel that connects to matrix.
Arginine residue is there to make glutamate lose proton, and hydrogen now flows out to matrix.
Explain why ATP synthase really only goes in one direction.
Because once glutamate loses proton, doesn’t want to go into bilayer, wants to go to inner channel that isn’t as hydrophobic. And glutamate that is currently there is protonated so it’s happy to go into bilayer.
ATP synthase has three general stages, Tight, loose, and open confirmations. What allows these diverse confirmations?
Driven by contact with gamma subunit.
ETC, electrochemical proton gradient, and ATP synthesis are all tightly coupled. Explain why this is true/how we know.
Oxygen consumption = ETC using oxygen.
Graph shows oxygen consumption is stoichiometrically link to substrate availability/ATP production.
What is Oligomycin, what is its purpose?
Inhibitor of ATP synthesis. Blocks key glutamate residue.
We know oligomycin only directly affects ATP synthase. How does it affect the rest of ETC?
Eventually, pumping protons out of the matrix becomes so thermodynamically unfavorable that the electron transport reactions can no longer achieve it.
Too low a concentration of ADP can also lose thermodynamic favorability.
Define respiratory control.
Driven by substrate availability of ADP, when high in volume, system works faster, when in low volume, ETC stops.
Chemical uncouplers, are chemicals that uncouple reactions. Give an example used in this class and explain how it works.
DNP: has titratable proton in the same pH gradient range across mitochondrial membrane as ETC.
DNP protonated is very permeable across membrane.
DNP transports H+ down chemical gradient without going through ATP synthase!
DNP seems like a great way to lose weight! Why does the FDA ban it?
Even though DNP is fatal, regulated uncoupling of oxidative phosphorylation can be good, give an example and why!
UCP-1 shortcurcuts coupling, helps create heat!
C: liver: ATP synthase doesn’t have substrate. Brown: still goes down gradient through UCP-1. Etc.
How much ATP is made:
How many protons pumped per NADH?
Experimentally complex 1 (NADH) yields how much ATP?
Experimentally complex 2 (FADH2) yields how much ATP?
Summary slide:
